BUZZ-Cancer drugs: Roche impresses in immunotherapy race

** Impressive results from Roche, following release of scientific summaries, or abstracts, ahead of big ASCO oncology conference in Chicago later this month

** Strong lung cancer data for anti-PD-L1 drug MPDL3280A support Roche's diagnostic-led approach and should enable company to file for accelerated U.S. approval in second half of 2015, Deutsche Bank (Xetra: 514000 - news) analysts say

** AstraZeneca (NYSE: AZN - news) data on PD-L1 drug MEDI4736 and tremelimumab combination in lung cancer looks "solid" and remains promising, according to Jefferies

** Bristol-Myers Squibb's leading position in immuno-oncology increasingly challenged by other contenders including Merck (Other OTC: MKGAF - news) , Roche, AstraZeneca and Pfizer (NYSE: PFE - news) , says Barclays (LSE: BARC.L - news)

** Key late-breaking presentations not included in initial abstracts release, pointing to more jockeying for position at May 29-June 2 ASCO scientific sessions

** AstraZeneca shares up 0.8 percent; Roche untraded in Zurich due to holiday (RM (LSE: RM.L - news) : ben.hirschler.thomsonreuters.com@reuters.net)